In general, a control program for controlling a plant is designed and created according to the requirements specification of the plant. The control program is installed in a control device that includes a plurality of programmable controllers. The control program is used after confirming that the required functions can be operated safely.
However, based on subsequent changes in the operation conditions of the plant, various modification requests such as changes, additions, and deletions need to be made on the control program.
When a provider of the control program receives a modification request on the operating control program such as the above, the provider needs to perform the modification work, by confirming whether the control program that is managed as a master control program in a providing source is matched with the operating control program, before starting the modification.
However, in a large-scale control system, large and small modifications are made multiple times on the control system by a lot of people during a long period of time. Because the quality of the modified control program is manually confirmed, the provider of the control program needs to spend a lot of time and effort every time a modification request is received.
Thus, a technology of automatically detecting changes, additions, and deletions on a plurality of parts in a control program has been disclosed.
For example, there is a control program maintenance method that includes: a dividing process of dividing an executable control program including an operation code and an operand into a single block of relating process step groups; a comparison process of comparing the two or more blocks of divided control programs; and an output process of outputting the comparison results.
Also, in the control system, in addition to the modification of the control program, a change may be made in conjunction with the moving of an input and output device or the like. To cope with such a case, an engineering device that is capable of reducing the time required for process of moving or changing the device and enables the process of moving or changing the device while preventing a design error has been disclosed.
In general, modification work (in this example, also referred to as maintenance work, and is used as a synonym) of a control program for controlling a plant is performed by a number of programmers. Thus, a control program maintenance system has been desired that can prevent human error and can clearly compare the modified parts before and after the change is made in a short period of time, and the modification content of the system can easily be shared among the workers.
The conventional control program maintenance method described above is capable of determining consistency, changes, additions, or deletions of the executable control programs at the divided control program level. However, it takes time to confirm the quality of the control program before and after the modification is made, because a large number of confirmations must be made.
The present invention has been made to solve the problem described above, and an object of the present invention is to provide a control program maintenance device, a control program maintenance method, and a program that can determine a modified part and a modified content in a control program in a short period of time; that can easily share the modification quality; and in which the maintenance quality and the maintenance work efficiency of the control program are improved; in the control program maintenance device for controlling a plant that is to be provided in a programmable controller of a control system.